We wish to study the early proteins of the bacteriophage T4 that participate in phage DNA replication. These proteins include enzymes responsible for both substrate biosynthesis and the polymerization process itself. We will study the regulation of the expression of these genes, as well as the interactions between the proteins that lead to faithful and rapid DNA synthesis. The regulation of expression of the "replisome" components probably reflects the capacity of T4 to respond to different environmental opportunities. We will try to understand the physiological aspects of T4 DNA synthesis. The approach taken in this research utilizes modern molecular biology, genetics, genetic engineering and biochemistry. As part of this work, we hope to elucidate the biochemical role of the T4 rII proteins, which apparently are replisome components. The total approach complements the more structural work in several other laboratories.